Novel herbicidal compositions

ABSTRACT

This invention relates to the use of certain 1,2-dialkyl-3,5diphenyl pyrazolium salts as herbicides. It also relates to herbicidal formulations of such salts. It further relates to certain novel pyrazolium salts. Finally, it relates to methods for the preparation and use of herbicidal formulations and novel salts.

United States Paten Walworth et al.

[ Nov. 25, 1975 I NOVEL HERBICIDAL COMPOSITIONS [75] Inventors: Bryant Leonidas Walworth,

Pennington; Erwin Klingsberg, Mountain Side, both of NJ.

[73] Assignee: American Cyanamid Company,

Stamford, Conn.

[22] Filed: Apr. 5, 1974 [21] Appl. No.: 458,367

Related U.S. Application Data [60] Division of Ser. No. 307,672, Nov. 17, 1972, which is a continuation-in-part of Ser. No. 271,424, July 13, 1972, abandoned, which is a continuation-in-part of Ser. No. 209,448, Dec. 17, 1971, abandoned.

[52] U.S. Cl. 71/92 [51] Int. Cl. A01N 9/22 [58] Field of Search 71/92 [56] References Cited UNITED STATES PATENTS 3,754,887 8/1973 Brantley 71/74 FOREIGN PATENTS OR APPLICATIONS 3,913,030 7/1964' Japan OTHER PUBLICATIONS Bulletin De La Societ Chim. de France No. 5, (1969), pp. 1687-1698.

Journal of General Chemistry, USSR Vol. 40 (1970) pp. 2057'to 2062.

Primary Examiner-Lewis Gotts Assistant Examiner-Catherine L. Mills Attorney, Agent, or Firm-Robert P. Raymond [57] ABSTRACT 18 Claims, No Drawings NOVEL HERBICIDAL COMPOSITIONS This application is a divisional of application Ser. No. 307,672, filed Nov. 17, 1972, which in turn is a con- 5 tinuation-in-part of application Ser. No. 271,424, filed July 13, 1972, now abandoned, which in turn is a continuation-in-part of application Ser. No. 209,448, filed Dec. 17, 1971, now abandoned.

This invention relates to the use of certain l,2-dialkyl-3,S-diphenylpyrazolium salts as herbicides. It also relates to herbicidal formulations of such salts. It further relates to certain novel pyrazolium salts. Finally, it relates to methods for the preparation and use of herbicidal formulations and novel salts.

More particularly, the herbicidal methods of the present invention relate to the control of undesirable plant species by applying to their foliage a herbicidally effective amount of a compound having the following formula:

wherein R and R each represent lower alkyl groups having one to four carbon atoms; Y, Y, Z and Z each independently represent a member selected from the group consisting of hydrogen, halogen, nitro, alkyl C -C haloalkyl C -C and alkoxy C -C X represents an anion with a charge of from 1 to 3; and m is an integer selected from 1, 2 and 3.

Suitable halogen substituents include, for example, fluoro, chloro, bromo and iodo. The chloro, bromo and fluoro are preferred.

Suitable alkyl substituents include methyl, ethyl, npropyl, iso-propyl, n-butyl, iso-butyl and tert-butyl.

Suitable alkoxy substituents include methoxy, ethoxy, n-propoxy, iso-propoxy, n-butoxy, iso-butoxy and tert-butoxy.

Suitable haloalkyl substituents are alkyl substituents, such as the above having substituted thereon one or more chloro, bromo or fluoro groups or mixtures thereof.

As will be apparent from the description and examples below, salts of the pyrazolium structure depicted in formula (1) above have unexpected herbicidal activity, irrespective of the anion employed in association therewith.

Illustrative of the anions which are suitable for use in the presegtlnvention may be mentioned, for example, halides, such as chloride, bromide or iodide; acetate; sulfate, hydroxide; hydrogen sulfate; methyl sulfate;

2 benzene sulfonate; C -C alkoxy benzene sulfonate; C -C alkyl benzene sulfonate, preferably a toluene sulfonate, such as, p-toluene sulfonate; nitrate; phosphate; carbonate; hydrogen carbonate; alkane sulfonate C,C.,; perchlorate; Br; and I With regard to the pyrazolium salts of formula (I), it is to be understood that certain multivalent anions such as sulfate, phosphate, and the like may have associated with them a cation in addition to the pyrazolium cation, as for example a proton or an alkali metal or alkaline earth 'metal.

For simplicity, such anions are portrayed as being unionized although they probably are in fact further ionized. Typical representations are: NaSOf, KPOf', MgPOf, H NaHPOf, and the like.

The plants which can be effectively controlled by application of one or more of the formula (I) pyrazolium salts include both broad leaf plants and annual grasses (monocotyledonous and dicotyledonous plants).

Generally preferred compounds for this use are those wherein the compound has the structure wherein Y, Y, Z and Z are hydrogen; R, and R are methyl; m is l and X is selected from the group consisting of chloride, bromide, iodide, acetate, hydroxide, hydrogen sulfate, methyl sulfate, p-toluene sulfonate, perchlorate and alkyl sulfonate C -C Especially preferred salts for this general use include l,2-dimethyl-3,S-diphenylpyrazolium p-toluenesulfonate, l,2-dimethyl-3,S-diphenylpyrazolium methyl sulfate, l,2-dimethyl-3-( m-chlorophenyl)-5-phenylpyrazolium methyl sulfate, l,2-dimethyl-3-(m-methylphenyl)-5-phenylpyrazolium methyl sulfate, l,2- dimethyl-3-(o-methylphenyl)-5-phenylpyrazolium methyl sulfate and l,2-dimethyl-3-(p-chlorophenyl)-5- phenylpyrazolium methyl sulfate.

This invention also relates to a method for the control of wild oats (Avena species) by application of a herbicidally effective amount of one or more of the formula (l) pyrazolium salts to the foliage thereof. Those wherein R is methyl; R is alkyl C -C Y, Y, Z and Z each independently represent a member selected from the group consisting of hydrogen, halogen, methyl and methoxy; provided that only one of the phenyl rings is substituted para to the pyrazolium ring with a substituent other than hydrogen are preferred. They effectively control the wild oats at unexpectedly low levels of application, such as at from 0.5 to 3.0'pounds per acre.

It is also a significant aspect of the present invention that such compounds permit the selective control of wild oats, e.g. Avena fatua, A. ludoviciana and A. sterilis growing in cereal grains, such as in wheat, barley and rye, and other crops which grow in wild oat infested areas, such as sugarbeets, rape, flax, sunflower, peas and potatoes.

Wild oats infestation in such crops as wheat and barley can drastically reduce crop yield by competition for sunlight, water and nutrients as well as cause crop contamination.

Few herbicides selectively control wild oats in crops such as wheat and barley. Those that are so employed generally present one or more disadvantages. For example, some are preemergence herbicides and thus require application before a determination can be made that an infestation exists. Others are only effective for the short period of time when the pest has one or two leaves. If spraying is delayed, such herbicides become uneffective. Others are only optimally employed with adult plants after tillering has occurred. In such cases the pest has already deprived the crop of nutrients, water and sunlight. Others, while highly selective on wheat, have only marginal selectivity on barley.

The advantages of the present invention lie in the good postemergence selectivity on wheat as well as being highly selective on barley, combined with herbicidal effectiveness throughout the early and middle life of the wild oat plant, together with their favorable dermal toxicity which is greater than 5,000 mg./kg. in rabbits for l,2-dimethyl-3,S-diphenylpyrazolium methyl sulfate, low eye irritation and acute oral toxicities (LD/SO) of about 580 mg./kg. and 50 mg/kg. in male rats and female mice, respectively, for said compound.

The pyrazolium salts are conveniently prepared by first condensing the appropriate diketone with hydrazine or a C -C lower alkyl hydrazine to form the corresponding 3,5-diphenylpyrazole. Thereafter, said pyrazole is alkylated to form the desired formula (I) pyrazolium salt.

When hydrazine is employed in the condensation, alkylations are effected at the l and 2 positions. Where a lower alkyl hydrazine is employed in the initial condensation, alkylation is effected at the 2 position. These reactions are graphically depicted as follows:

4 include, for example, aprotic solvents, such as, xylene, toluene, benzene, pyridine, DMSO, DMS, and the like, or protic solvents, such as, C -C alcohols, preferably, nand iso-propanol. Where the latter solvents are employed, high rates of conversion are obtained at temperatures in the range of 80C. to 85C.

Where hydrazine is employed in the initial condensation reaction, alkylation of the resulting pyrazole is accomplished with conventional alkylating agents, preferably in the presence of an acid acceptor, such as an alkali metal hydroxide or alkoxide, or a tertiary organic amine. Suitable bases include, for example, sodium methoxide, sodium hydroxide, triethylamine and the like.

The alkylation reactions are preferably conducted in the presence of a solvent, such as toluene, methylisobutyl ketone, nor iso-propanol or an aqueous alcohol solution, such as a mixture of n-propanol and water.

Suitable alkylation reagents include, for example, alkyl halides alkyl acetates, alkyl sulfates, alkyl nitrates, alkyl phosphates, alkyl carbonates, alkyl perchlorates, alkyl hydrogen sulfates, alkyl methyl sulfates and alkyl toluene sulfonates; wherein, said alkyl groups are in the range of from C -C to provide the appropriate alkyl Ion Exchange Option 0 O H H C-CHg-C Z Z I RNHNH II Alkylation Y X (see below) wherein m, R R Y, Y, Z, Z and X are as described substituent in the formula (1) compound. Anion exfor formula (I) above; and R is hydrogen or lower alkyl Of C1-C4.

Since the diketone and hydrazine compounds combine in equimolar quantities, it is preferable to maintain the molar ratio of reactants at about 1:1; however, a slight excess (up to about 10%) of either reactant may be used.

The ring-forming reaction between the hydrazine or alkyl hydrazine and the diketone is preferably carried out by combining the reactants in a solvent and heating to the reaction temperature. Suitable temperatures are in the range of from about C. to about 150C. and, preferably, between C. and C. Suitable solvents change can be used to associate the desired anion or anion mixture with the cation desired, as described below.

The pyrazole and alkylating reagent combine on an equimolar basis. However, it is often preferred to employ an excess of the alkylating agent. Optimum reaction conditions for effecting the alkylations will vary depending on the reactants employed. Reaction is effected by combining the alkylating agent, the pyrazole and, preferably, the acid acceptor and solvent. Reaction often occurs at room temperature. If not, the reaction mixture is heated until the reaction occurs. Where the alkylating reagents employed are volatile, such as methyl chloride, the reaction is preferably conducted in a sealed vessel under pressure, to avoid loss of the reactants.

Quaternization of the l-alkylpyrazole is effected by reaction thereof with at least an equimolar quantity of 5 an alkylating agent, such as those mentioned above.

This reaction is preferably conducted in the presence of a solvent, such as, a lower alcohol C -C a ketone, such as, acetone, methyl isobutyl ketone, methyl ethyl ketone or cyclohexanone; a chlorinated hydrocarbon, such as, chloroform; an ether, such as diethyl ether, methyl ethyl ether or di-n-propyl ether; an aprotic solvent, such as dimethyl sulfoxide or dimethylformamide; or, preferably, an aprotic solvent, such as xylene, toluene or benzene.

The quaternization is effected by mixing the reactants and solvent at temperatures maintained between 35C. and 150C., preferably between 50C. and 125C.

Since the l-alkylpyrazole and alkylating reagent combine in equimolar quantities, it is preferred to employ a 1:1 molar ratio thereof; however, a slight excess (up to of either reagent may be employed.

As in the previously discussed alkylation reaction, where the alkylating agent is volatile at the temperatures used, such as in the case of methyl chloride, it is preferred to use a sealed pressure vessel to conduct the reaction.

Where the diketone selected is asymetrically substituted and R differs from R in the formula (I) compound to be produced, a mixture of isomers will result from the above synthetic scheme. In such cases, it is generally expedient to employ the isomer mixture in the herbicidal processes of the present invention. Where their separation is desired, however, it may be effected by conventional separation techniques, such as, for example, by fractional crystallization.

In carrying out the above ring closure and alkylation reactions, it may be expedient to initially form a salt having an anion other than that which it is desired to employ in the herbicidal processes of the present invention. In such cases, the exchange in anion may be conveniently made in a subsequent step, such as that graphically depicted below:

wherein m, R,, R Y, Y, Z and Z are as defined for formula (1) above; m is an integer selected from 1, 2 and 3; and W is an anion.

The exchange may be effected by treating the ini- -tially formed salt with an ion exchange resin. Among Other optional subsequent modifications of the anion in the pyrazolium salt may be effected. For example, a pyrazolium chloride may be conveniently converted to the corresponding bromide or iodide by treatment with NaBr or Nal, respectively, in a solvent, such as acetone. A pyrazolium salt, such as, the'chloride may be converted to the corresponding perchlorate by treatment of an aqueous solution of said salt with perchloric acid. This results in the precipitation of the less soluble perchloride salt. The bromides or iodides may be conveniently converted to the tribromides or triiodides by adding bromine or iodine to a solution of the monobromide or monoiodide in a solvent, such as ethanol.

The novel compounds of the present invention are those having formula (I) provided that X is not I, C10, or Cl when Y, Z, Y and Z are hydrogen and R, and R are methyl.

The compound 1,2-dimethyl-3,S-diphenylpyrazolium iodide is disclosed in Bulletin De LaSocit Chimique De France No. 5, pages 168798 (1969). The corresponding perchlorate is disclosed in Zhurnal Obshcher Khimii, Vol. 40, No. 9, pages 2072-8 (September, 1970), the English version of which appears in the Journal of General Chemistry, U.S.S.R. 40, pages 2057-2062 (1970). While the corresponding chloride does not appear to have been known as a pure composition of matter (that is, as the pure compound per se) 7 it may have been present, although unnamed, in the form of an impure composition employed in the synthesis of the perchlorate mentioned above.

Notwithstanding the above art, there is nothing to suggest the present utility of the formula (I) pyrazolium salts or the advantages of the preferred compounds therein.

As previously noted, the compound l,2-dimethyl- 3,5-diphenylpyrazolium chloride does not appear to have been mentioned in the prior art. However, it may have been present in the reaction mixtures reported in the Russian Journal in combination with various impurities. The impurities of the reaction mixture appear to cause severe foliar burn to such crops as soybeans, cotton and corn in comparison with the use thereon of 1,2- dimethyl-3,S-diphenylpyrazolium chloride per se. Since the chloride component of the reaction mixture had no known utility, no attempt was made to isolate it as the pure compound per se or even establish its existence. One advantage to the hydrazine and alkyl hydrazine process of manufacture described above over the dimethyl hydrazine hydrogen chloride process of the Russian article resides in the formation of the pyrazole intermediate IV which may be purified by conventional purification techniques (distillation, crystallization, etc.) prior to the alkylation reaction, where such purification steps are desired or desirable.

As will be noted below, those pyrazolium salts which demonstrate a high degree of water solubility possess substantial advantages in the preparation of water miscible concentrates. Among the preferred salts in this regard are the methyl sulfates, hydrogen sulfates, sulfates, bromides, tosylates and the chlorides (free of adverse impurities such as those occurring in the method of the Russian reference). Specifically, preferred salts are the 1,2-dimethyl3,5-diphenylpyrazolium salts of the above anions, which provide about 1.6 to about 2.2 milliequivalents of the pyrazolium cation per gram of aqueous solution at about l8C.-23C. as opposed to salts such as the corresponding perchlorate and iodide, which only provide about .002 to 0.3 milliequivalents of the cation per gram of aqueous solution.

l,2-Dimethyl-3,5-diphenylpyrazolium methyl sulfate is especially preferred by reason of its excellent herbicidal activity, as shown, for example, below and due to the relative convenience by which it may be prepared from inexpensive materials. The pyrazolium methyl sulfate is prepared using dimethyl sulfate as the quatemizing agent for the appropriate pyrazole. The dimethyl sulfate is far less expensive and easier to employ than the low boiling methyl chloride and iodide employed in the direct synthesis of the pyrazolium chloride and iodide.

In comparison with the iodide and the perchlorate, the methyl sulfate has the added advantage of providing about 70 and 525 times the milliequivalents of pyrazolium cation respectively.

In applying the formula (I) pyrazolium salts to the foliage of the undesirable plant species, the salts are preferably formulated as post-emergence herbicidal compositions by admixing a herbicidal adjuvant with a herbicidally effective amount of the salt. Suitable adjuvants include one or more conventional solid or liquid carriers, diluents and formulation aids, particularly surfactants. The salts may be formulated alone, in combination with each other or with other pesticidal agents. The water-miscible concentrates discussed below are especially advantageous. The present invention is fur- 8 ther directed thereto as well as to methods for their preparation and use.

Application of the salts as dusts, dust concentrates, wettable powders and water-miscible compositions using conventional application equipment at rates of from 0.25 to 20 pounds of active ingredient (i.e., cation) per acre are preferred.

Dusts are generally prepared by grinding together about 1% to 25% by weight of the active agent with from about 99% to by weight of a solid diluent such as kaolin, attapulgite, talc, pumice, diatomaceous earth, fullers earth, wood flour, or the like. Dust concentrates are prepared in similar fashion excepting that about 25% to 95% by weight of the active agent is ground with about 75% to 5% by weight of the diluent.

Wettable powders are prepared in the same manner as the dust concentrates excepting that about 1% to 5% by weight of a dispersing agent such as the calcium salt of a polymerized alkyl aryl sulfonic acid, sodium lignosulfonate, or sodium salt of condensed naphthalene sulfonic acid is blended with the mixture and about 1% to 5% of a surfactant, such as polyoxyethylated vegetable oil, alkyl phenoxy polyoxyethylene ethanol, sodium alkyl naphthalene sulfonate is also blended with the formulation.

The water-miscible concentrates are prepared by dissolving from 15% to 70% of the compound in to 30% of a water-miscible solvent, such as water itself or another polar water-miscible solvent, such as 2- methoxy ethanol, methanol, propylene glycol, diethylene glycol, diethylene glycol monoethyl ether, formamide, and methylformamide. Application of the material is made by adding a predetermined quantity of the water-miscible concentrate to a spray tank and applying as such or in combination with a suitable diluent, such as after addition of a further quantity of water or one of the above polar solvents.

The performance of the product in all of the above formulations, which are applied as liquid sprays, is unexpectedly improved by adding a surfactant or blend of surfactants. Conventional anionic, cationic and anionic-nonionic surfactants may be employed.

Suitable nonionic surfactants include alkyl polyoxyethylene ethers, polyoxyethylene (20) sorbitan monolaurate, polyoxyethylene (20) sorbitan monooleate, alkylarylpolyglycol ethers, alkyl phenol ethoxylates, trimethyl nonyl polyethylene glycol ethers, alkyl phenol ethylene oxide condensates, octyl phenoxy polyethoxy ethanols, nonylphenyl polyethylene glycol ethers, condensates of polyoxy ethylenes, polyoxy propylenes, aliphatic polyethers, aliphatic polyesters, alkylaryl polyoxyethylene glycols, and the like.

Suitable anionic surfactants include sodium dodecylbenzene sulfonate and the dioctyl ester of sodium sulfosuccinic acid.

Suitable cationic surfactants include dicoco dimethylammonium chloride, stearamidopropyl dimethyl beta-hydroxyethylammonium nitrate and the like.

These surfactants are preferably added to the spray tank at the rate of 0.1% to 5% by volume to provide good wetting of the spray solution on plant foliage.

Herbicidal concentrates containing surfactants are preferably formulated as aqueous sprays containing approximately 29% by weight of the appropriate salt, from about 26% to 50% by weight of water and the remainder of said formulation (26%-44% weight weight) of a selected surfactant. Surfactants which have been used in preparing suitable surfactants containing concentrates include an octylphenol ethylene oxide condensate, an ethanolic solution of an alkyl phenol ethoxylate, a polyglycolic ether condensate produced from ethylene oxide and an alkyl phenol and an alkyl aryl polyglycolic ether. Typical formulations are (1) 28.6% of l,2-dimethyl-3,5 -diphenyl pyrazolium methyl sulfate, 27.0% of one of the above surfactants and 49.4% water; and (2) 28.6% of l,2-dimethyl-3,5-diphenyl pyrazolium methyl sulfate, 44% of one of the above surfactants and 24.7% water.

In control of wild oats, preferably about 2 quarts of the concentrate containing surfactant (1 would be admixed with 20 gallons of water and applied as a dilute aqueous spray to cover 1 acre of treated area. This spray solution would contain approximately 0.5% by weight of the surfactant. Formulation (2) would prefer ably be used in a similar manner except that 2 quarts of the formulation would be admixed with 40 gallons of water and applied as the dilute aqueous spray to cover 1 acre of treated area.

It is, of course, obvious that the formulations can be varied to provide dilute aqueous sprays containing from about 0.1% to 5.0% by weight of the surfactant and a herbicidally effective amount of the pyrazolium salt.

As previously noted, the water-miscible herbicidal concentrates of the present invention are prepared by dissolving to 70% of a pyrazolium salt of formula (I) in 85% to 30% of a water-miscible polar solvent. These compositions are unexpectedly improved with regard to herbicidal effectiveness by the further step of adding a surfactant. Nonionic, anionic or nonionicanionic blends may be employed. Nonionic surfactants are preferred, especially those having a hydrophiliclipophilic balance (HLB) of from 11 to 16. This conventional surfactant classification test is described, for example, at page 232 et seq of Emulsion Theory and Practice by Paul Becher, Rheinholt Publishing Corporation, second edition (1965 also available as No. 162 in the American Chemical Societys Monograph Series.

Preferred methods employ water as the solvent and 1,2-dimethyl-3,5-diphenyl pyrazolium methyl sulfate as the active ingredient.

These compositions are effective for the postemergence control of undesirable plants when applied at a rate sufficient to provide 0.25 lbs/acre of active ingredient (i.e., cation. Application at rates of from about 0.5 lb. to 10 lbs. per acre of said active material are more preferred. For selective postemergence control of wild oats, about 0.50 lb. to 3.0 lbs. per acre of active material (i.e., cation) are usually preferred.

The present invention and preparation of the starting materials therefor are further illustrated by the following examples which are not to be taken as being limited thereto. Unless otherwise indicated, all parts and percentages are by weight, in the following illustration and examples as well as in the claims and the discussion above.

Preparation of the dibenzoyl methane starting materials is exemplified by Illustration A below for m-trifluoromethyl dibenzoyl methane.

A variety of suitably substituted dibenzoyl methanes for use in the present invention are commercially available or may be conveniently prepared by a variety of procedures well known in the chemical literature from readily available starting materials, such as the appropriately substituted acetophenone and appropriately substituted benzoic acid compounds or esters thereof.

Among the readily available dibenzoyl methanes may be mentioned the 1,3-propane diones having the following 1,3-radicals: 1,3-diphenyl; 1,3-di-p-tolyl; l-(o methoxyphenyl)-3-phenyl; l-(p-methoxyphenyl)-3- phenyl; l-(o-nitrophenyl)-3-phenyl; 1-(p-nitrophenyl)- 3-phenyl; 1-(m-nitrophenyl)-3-phenyl; l,3-bis(pfluorophenyl); l,3-bis(p-iodophenyl); 1-(3-bromo-4- methoxyphenyl)-3-phenyl; 1-(p-bromophenyl)-3-phenyl; 1-(p-chlorophenyl)-3-phenyl; 1-(3,4dichlorophenyl)-3-phenyl; 1-(5-bromo-2-methoxyphenyl)-3- (bromophenyl); l-(5-bromo-2-methoxyphenyl)-3-phenyl; and 1-(3-bromo-4-methoxyphenyl)-3-p-tolyl and 1-(m-trifluoromethylphenyl)-3-phenyl.

Suitable benzoic acid derivatives useful in the preparation of the halo alkyl dibenzoyl methanes include, for example, those having the following substituents: p-trichloromethyl; o-dibromomethyl; o-2,2,2-trichloroethyl; p-l,2-dibromoethyl; o-dichloromethyl; obromomethyl; m-2,2-dibromoethyl; p-2-chloroethyl; p-3-chloropropyl and the like.

ILLUSTRATION A Preparation of l-Phenyl-3-(m-trifluoromethylphenyl)-propane-1,3-

- dione 68.4 Grams (0.335 mole) of the methyl ester of mtrifluoromethyl benzoic acid are combined with 36.0 grams (0.3 mole) of acetophenone in 200 ml. of dimethylsulfoxide. 8.04 Grams (0.335 mole) of sodium' hydride as a 54% mineral oil composition were added and the reaction mixture was stirred overnight. 10 Ml. of phosphoric acid was then added to 500 ml. of ice water. The reaction mixture was then added to the ice water composition with stirring until room temperature was achieved. 300 Ml. of water was then added and the solid precipitate which formed was removed by filtration, water washed and dried to produce the desired product having a melting point of 6062C. Purification was effected by recrystallization in ethanol to give a product having a melting point of 63-64C.

EXAMPLES l-7 Preparation of l-Methyl-3,S-diphenylpyrazole CHa-NH-NH (VII) (VIII) I ca 545.0 Grams (2.43 moles) of dibenzoylmethane and 533 ml. of pyridine are stirred together and heated to 80C. 1 12 Grams (2.43 moles) of methylhydrazine are then slowly added to the mixture and a strong exothermic reaction ensues necessitating cooling of the mixture with a water bath. When addition is complete, the mixture is heated to reflux and maintained in this condition for 40 minutes. The mixture is then cooled to 30C., poured into 19 liters of 3N HCl, filtered, and the solid collected. This is reslurried in 198 grams (2.43 moles) of sodium acetate dissolved in 19 liters of water. The mixture is filtered, water washed and air dried to give 535 grams of product, 94.5% yield, having melting point 58C. to 59C.

Following the above procedure and substituting ethylhydrazine, n-propylhydrazine, isopropylhydrazine, sec-butylhydrazine, n-butylhydrazine, or isobutylhydrazine for methylhydrazine in the above reaction yields respectively: 1-ethyl-3,S-diphenylpyrazole; l-npropyl-3,S-diphenylpyrazole; 1-isopropyl-3,5-diphenylpyrazole; l-sec-butyl-3,S-diphenylpyrazole; l-n-butyl- 3,5-diphenylpyrazole; and 1-isobutyl-3,5-diphenylpyrazole.

zoylmethane with the appropriate alkylhydrazine under the conditions of Example 1 results in the preparation of l-alkyl-3,5-substituted diphenylpyrazoles. Graphically, the process may be illustrated as follows:

Among the compounds which can be prepared by this reaction are those identified in the table below. For compounds in this table, Y and Z are both hydrogen.

TABLE I No. Y Z R mp C.

30 8 Cl (3) H CH 9 Cl (4) H CH l27.5l28.5

[0 Br (4) H CH ll N0 (2) H C H l2 CH (4) H CH 101.5-[03 l3 OCH;, (3) H CH;,

14 OCH: (4) H CH l05-|06.5

l5 Cl(3) Cl (4) CH l6 Br (3) Br (5) C H l7 Br(3) CH4) CH 18 CH, (2) CH (6) CH l9 OCH (3) OCH; (4) C H n 21 Br (3) H C H -n 40 22 CH; (4) Cl (3) CH 23 CH; (3) OCH; (4) CH;

24 NO; (2) NO, (6) CH 25 NO, (3) Br (4) C H 26 OCH: (4) H C., H -sec 27 CF; (3) H CH EXAMPLE 28 Preparation of l,2-Dimethyl-3,S-diphenylpyrazolium p-toluene sulfonate CH O -CH (XIII) 400 Grams (1.71 moles) of l-methyl-3,5-diphenylpyrazole is dissolved in 2100 ml. of xylene and the solution thus prepared dried by azeotropic distillation. The solution is cooled to 70C. and 318 grams (1.71 moles) of methyl-p-toluene sulfonate is added. The mixture is then refluxed for one hour and cooled causing the product to crystallize. When the mixture is cooled to 40C., 1000 ml. of acetone are added. The mixture is filtered, washed with acetone, and dried in vacuo yielding 495 grams (69%) of product having a melting point of 177C. to 178C.

EXAMPLE 29 Preparation of l,2-Dimethyl-3,S-diphenylpyrazolium iodide 5.0 Grams of 1-methyl-3,S-diphenylpyrazole is dissolved in 30 ml. of dry benzene with heating and constant stirring. 30.4 Grams of methyl iodide is added to the mixture, and the mixture heated to reflux. After refluxing for 12 hours, the mixture is cooled and filtered. The filtrate is again refluxed and as product forms, it is separated from the mixture by filtration. The total amount of solid recovered is 1.21 grams, 15% yield, having a melting point of 167C. to 169C.

EXAMPLE 30 Preparation of 1,2-Dimethyl-3,S-diphenylpyrazolium sulfate and methyl sulfate 5.0 Grams of l-methyl-3,5-diphenylpyrazole is dissolved in 30 ml. of dry xylene with heating and constant stirring. The solution is cooled to 60C., and 2.78 grams of dimethyl sulfate is added in 10 ml. of xylene. The mixture is then heated to 100C. for 6 hours and al- .lowed to cool. After cooling, the mixture is filtered.

The solid which is recovered is stirred with dry acetone and the mixture filtered.

This yields 3.91 grams of the methyl sulfate, 50.7% yield, having a melting point of 146C. to 148C.

The filtrate is then evaporated to remove acetone and the remaining residue is collected. The residue weight of 1.23 grams, 16.6% yield, is the desired sulfate having a melting point of 188C. to 189.5C.

EXAMPLES 3 146 Following the general procedures of Examples 28, 29 or 30, substituting the appropriately substituted 1- alkyl-3,5-substituted diphenylpyrazole for l-methyl- 3,5-diphenylpyrazole and the appropriate alkyl-p-toluene sulfonate, alkyl halide or alkyl sulfate for the methyl-p-toluene sulfonate, methyl iodide or dimethyl sulfate, yields the corresponding 1,2-dialkyl substituted 3,5-diphenylpyrazolium salt. The reaction is graphically illustrated below:

wherein R R X, Y, Y, Z, Z and m are as described above for (1).

Among the compounds which can be prepared by this reaction are those identified in the table below where Y and Z are both hydrogen, and m is l.

EXAMPLE 47 Preparation of 3,5-Diphenylpyrazole 22.4 Grams (0.10 moles) of dibenzoylmethane in 200 ml. of isopropyl alcohol are heated to reflux (approximately 85C.), and to this is added hydrazine hydrate at a rate sufficient to maintain reflux. Thirty minutes after addition, the reaction is complete. The reaction mixture is permitted to cool and is then poured into water. The desired product as a fine white solid precipitatesand is filtered, washed with cold water and dried, yielding 22.1 grams of product, melting point 198.5C. to 200.5C.

EXAMPLE 48 Preparation of 1-Methyl-3,S-diphenylpyrazole EXAMPLE 49 Preparation of l-Methyl-3,S-diphenylpyrazole 5.0 Grams of dibenzoylmethane in 40 ml. of isopropanol is heated to 50C. The temperature of the reaction mixture is then raised to about 85C. and 10.5 grams of methyl hydrazine in ml. of isopropanol added thereto. The mixture is heated at this temperature for 30 minutes, then cooled and cold water added thereto. A white solid precipitate forms and is filtered, washed and dried to yield 5.22 grams of product having a melting point of 595C. to 60C., 99+% yield.

EXAMPLES 50-51 Preparation of 1-Methyl-3,S-diphenylpyrazole 2.20 Grams (0.01 moles) of 3,5-diphenylpyrazole is mixed with 0.4 grams of sodium hydroxide in 3 ml. of water. To this mixture is added 1.32 grams (0.01 moles) of dimethylsulfate in 5 ml. of n-propyl alcohol. During addition, the temperature of the reaction mixture is maintained below 30C. by means of an ice bath, but when addition is complete the temperature is increased to 40C. The mixture is then poured into water where a solid forms, is filtered off, washed with water and dried to give 2.18 grams of the desired product, 53% yield.

The above procedure is repeated with the exception that 0.54 grams of sodium methoxide is substituted for the sodium hydroxide and water. 2.34 Grams of the desired product are obtained with an improvement in yield to 77%.

EXAMPLE 5 2 Preparation of 1-Methyl-3,S-diphenylpyrazole Methyl chloride is condensed in a pressure vessel at 45C. At this temperature, 2.20 grams (0.01 moles) of 3,5-diphenylpyrazole dissolved in n-propanol (dry) are added slowly. Then sodium methoxide dissolved in 25 ml. of dry propanol is added and the pressure vessel sealed. The pressure vessel is brought to room temperature and stirred overnight and then heated to 40C. to 45C. for 8 hours. The reaction mixture is poured into water where a white solid forms. The mixture is filtered and the solid washed with water and dried, yielding 2.21 grams of the desired product, 55% yield.

EXAMPLE 53 Preparation of 1,2-Dimethyl-3,S-diphenylpyrazolium Perchlorate 4.7 Grams (0.02 moles) of l-methyl-3,5-diphenylpyrazole is added to a solution of methyl chloride, 1.5 grams (0.03 moles) in 35 ml. of n-propanol maintained at 40C. The mixture is then heated to C. and evaporated to a bright green oil. On addition of hexane and cooling, the crude pyrazolium chloride as a green solid precipitates. The solid is washed with water and dissolved in 60 ml. of H 0 and then HClO, added. The pyrazolium perchlorate as a white precipitate forms. It is filtered, washed with water and dried to yield the desired product.

EXAMPLE 54 Preparation of 1,2-Dimethyl-3,S-diphenylpyrazolium Methylsulfate 2.34 Grams (0.01 moles) of 1-methyl-3,5-diphenylpyrazole is added to 10 ml. of isopropanol and heated to 60C. 1.5 Grams (0.012 moles) of dimethylsulfate in 2 ml. of isopropanol is then added, and the mixture heated to reflux for 48 hours. The mixture is then cooled, filtered, slurried in dry acetone and refiltered and dried to give the desired product having a melting point of 147C. to 150C.

EXAMPLE 55 Preparation of 1,2-Dimethyl-3,S-diphenylpyrazolium Methylsulfate 375 Grams (1.6 moles) of l-methyl-3,5-diphenylpyrazole is dissolved in 1850 ml. of dry xylene and heated to 60C. 208.13 Grams (1.65 moles) of dimethylsulfate in 150 ml. of dry xylene is then added and the temperature of the reaction mixture raised to C. to C. and maintained there for 7.5 hours. The mixture is allowed to cool and then filtered. A brown solid is recovered, washed with xylene and then dry acetone to give the product in 88% yield, having a melting point of C. to 157C.

EXAMPLE 56 Preparation of 1,2-Dimethyl-3,S-diphenylpyrazolium bromide A glass column is packed with a commercial grade of a trimethyl benzyl ammonium chloride, strong base organic anion exchange resin. The resin is washed thoroughly with an aqueous sodium bromide solution of 1 N concentration until Br ion is detected in the eluent. Then an aqueous solution of l,2-dimethyl-3,5- diphenylpyrazolium p-toluene sulfonate is passed down the column at a slow rate. The eluent is concentrated in vacuo, leaving the desired product as a residue after drying with a melting point of l88C.-189C.

Analysis: Calcd. for C H N Brz C, 62.01; H, 5.22; N, 8.54; Br, 24.22. Found: C, 61.98; H, 5.30; N, 8.54; Br, 24.27.

EXAMPLES 57-62 Following the general procedure of Example 56 above, substituting the appropriate sodium salt for the sodium bromide used therein and the appropriate pyrazolium p-toluene sulfonate for that used therein C yields the compounds having the following formula and 5 (3 l substituents set forth in the table below. Y Y

(XVIII) l0 TABLE IV I (XVII) Substituents Ex. No. Y Z R R1 mp. "C I I 64 Cl (4) H CH CH 192.5-194 R1 R2 65 H H CH: -C,i-|,-n 145-1465 66 CH (4) H CH CH 132-134 67 CH;,O (4) H CH CH 159.5-161 TABLE III 7 EXAMPLE 68 x Preparation of l,2-Dimethyl-3,5-diphenylpyrazolium 57 1005-103 CH, CH 0H-(3H,0) triiodide 58 56-58 CH, CH *4 SO -(2H,O) 59 l40l4l.5 CH, CH N0 To a solution of 2.0 grams (0.0053 moles) of 1,2- 60 [88-189 CH CH Br 61 179548 CM 20 dimethyl 3,5 dlphenylpyrazohum iodide in 100 ml. of 62 163469 CH3 CH3 aqueous ethanol (1:1) was added 1.34 grams (0.0053 moles) of iodine. The reaction mixture was allowed to sit with the resultant formation of a red precipitate.

The precipitate was collected by filtration, washed EXAMPLE 63 with aqueous ethanol and air dried to produce 3.0

Preparation of 1,2-Dimethyl-3,S-diphenylpyrazolium grams of the desired triiodide having a melting Point of perchlorate 108-1 10C. and the following elemental analysis:

Calculated: C, 32.41%; H, 2.72%; N, 4.44%; I,

501mm Of 61.45%. Found: c, 32.23%; H, 2.78%; N, 4.43%; I, pyrazolium p-toluene sulfonate (10.0 g.) in 500 ml. of 60 29% water is added a 20% aqueous solution of perchloric acid with vigorous stirring. The product separates immediately as a white solid. It is collected by filtration, washed with water and dried to give 8.3 g. of the desired product having a melting point of 183C.- 184C., and the following elemental analysis:

Calcd. for C -,H ClN O :C, 58.75; H, 4.92; N, 8.05. Found: C, 58.21; H, 4.84; N, 7.95.

EXAMPLES 69-104 Following the general ring closing procedure of Example 1 and the alkylation procedure of Example 31, employing methylhydrazine and the appropriate diketones and alkylating agents yields the pyrazolium salts of the following formula, having the substituents set forth in the table below.

EXAMPLES 64-67 Following the general procedure of Example 63, substituting the appropriate pyrazolium p-toluene sulfonate for that used therein results in the formation of the perchlorates set forth in the table below.

EXAMPLES 105-106 Preparation of 1,2-Dimethy1-3,S-diphenylpyrazolium sulfate and hydrogen sulfate To a dry xylene (30 ml.) solution of 1-methyl-3,5- diphenylpyrazole (5.0 g., .02 mole) at 60C. was added dimethylsulfate (2.78 g., 0.022 mole) in xylene ml.). The reaction mixture was stirred and heated at 100C. during 6 hours, cooled to room temperature and set aside overnight. A crystalline solid was filtered off, washedvwith dry acetone and filtered to give the methyl sulfate 3.91 grams, m.p. 146-148C.

The acetone filtrate was evaporated to a solid residue which was washed with ice cold acetone, filtered and dried to give 1.23 grams (17%) of the hydrogen sulfate having a melting point of 188-189.5C.

EXAMPLES 107-139 The selective postemergence herbicidal activity of the compounds of the present invention is demonstrated by the following test, wherein a variety of monocotyledonous and dicotyledonous plants are treated with test compounds dispersed in aqueous acetone mixtures. In the tests, seedling plants are grown in jiffy flats for about 2 weeks. The test compounds are dispersed in 50/50 acetone/water mixtures containing 0.5%'Tween 20, a polyoxyethylene sorbitan monolaurate surfactant by Atlas Chemical Industries, in sufficient quantity to provide the equivalent of about 0.5 lb. to 9 lbs. per acre of active compound when applied to the plants through a spray nozzle operating at 40 psi. for a predetermined time. After spraying, the plants are placed on greenhouse benches and are cared for in the usual manner, commensurate with conventional greenhouse practices. Two weeks after treatment, the seedling plants are examined and rated according to the rating system provided below. The data obtained are reported in Table VI where it can be seen that the compounds are uniquely effective for the control of wild oats. The specificity is demonstrated by the findings that wheat is not injured or only very mildly affected by the compounds at rates which provide effective control of the wild oats.

Difference in Growth Rating System: from the Check 0 no effect 0 l possible effect 1-10 2 slight effect 1 1-25 3 moderate effect 26-40 5 definite injury 41-60 6 herbicidal effect 61-75 7 good herbicidal effect 76-90 8 approaching complete kill 91-99 9 complete kill 4 abnormal growth. that is, a definite physiological malformation but with an over-all effect less than a 5 on the rating scalev Based on visual determination of stand, size. vigor. chlorosis, growth malformation and over-all plant appearance. 

1. A METHOD FOR THE CONTROL OF UNDERSIRABLE PLANT SPECIES COMPRISING APPLYING TO THE FOLIAGE OF SAID UNDESIRABLE PLANTS A HERBICIDALLY EFFECTIVE COMPOUND HAVING THE FORMULA:
 2. A method according to claim 1 wherein the compound has the structure wherein Y, Y'', Z and Z'' are hydrogen; R1 and R2 are methyl; m is 1 and X is selected from the group consisting of chloride, bromide, iodide, acetate, hydroxide, hydrogen sulfate, methyl sulfate, p-toluene sulfonate, perchlorate and alkyl sulfonate C1-C4.
 3. A method according to claim 1 wherein the compound is 1,2-dimethyl-3,5-diphenylpyrazolium p-toluenesulfonate.
 4. A method according to claim 1 wherein the compound is 1,2-dimethyl-3,5-diphenylpyrazolium methyl sulfate.
 5. A method according to claim 1 wherein the compound is 1,2-dimethyl-3-(m-chlorophenyl)-5-phenylpyrazolium methyl sulfate.
 6. A method according to claim 1 wherein the compound is 1,2-dimethyl-3-(m-methylphenyl)-5-phenylpyrazolium methyl sulfate.
 7. A method according to claim 1 wherein the compound is 1,2-dimethyl-3-(o-methylphenyl)-5-phenylpyrazolium methyl sulfate.
 8. A method according to claim 1 wherein the compound is 1,2-dimethyl-3-(p-chlorophenyl)-5-phenylpyrazolium methyl sulfate.
 9. A method according to claim 1 wherein the undesirable plant species is wild oats and the compound has the structure wherein R1 is methyl; R2 is alkyl C1-C4; Y, Y'', Z and Z'' each independently represent a member selected from the group consisting of hydrogen, halogen, methyl and methoxy; provided that only one of the phenyl rings is substituted para to the pyrazolium ring with a substituent other than hydrogen.
 10. A method according to claim 9 wherein the compound is applied at a rate of from 0.5 to 3.0 pounds per acre.
 11. A method according to claim 9 for selectively controlling wild oats in the presence of a cereal grain crop by application of the compound to the wild oat infested crop.
 12. A method according to claim 11 wherein application is made by spraying an aqueous solution of said compound and a surfactant selected from the group consisting of nonionic; anionic and nonionic-anionic surfactants.
 13. A method according to claim 12 wherein the surfactant is nonionic and has a hydrophilic-lipophilic balance of from 11 to
 16. 14. A method according to claim 11 wherein the compound is 1,2-dimethyl-3,5-diphenylpyrazolium methyl sulfate.
 15. A method according to claim 12 wherein the compound is 1,2-dimethyl-3,5-diphenylpyrazolium methyl sulfate.
 16. A method according to claim 9 wherein the cereal grain crop is wheat.
 17. A method according to claim 9 wherein the cereal grain crop is barley.
 18. A method according to claim 9 wherein the cereal grain crop is rye. 